Microelectronic devices such as IC (integrated circuit) packages typically include a substrate to facilitate interconnections between an integrated circuit, referred to herein as a “semiconductor die,” and external structures. One purpose of the substrate in such packages is to redistribute the relatively closely-spaced contacts formed on the semiconductor die to a larger pattern of external interconnect contacts (pinout) spread over a greater area of the substrate to facilitate electrical and mechanical attachment, such as through contact balls, to a printed circuit board (PCB) or other structure.
In conventional IC packages, because the package substrate will typically redistribute all contacts of a semiconductor die, the substrate may occupy a relatively large area relative to the area of the semiconductor die. However, for some types of semiconductor die, not all applications will require communication with all contacts of the semiconductor die, and thus the dimension of substrate required to provide external interconnect contacts for all die contacts may be disadvantageous for space-sensitive applications. Additionally, a larger IC package size will normally result in increased cost of the package. In some applications, such as those using die having a high count pinout, redistributing all die contacts to the lower surface of the substrate may require multiple conductor levels in the substrate, further adding both to the cost and the height of the package.
Additionally, the redistributed pattern of the external interconnect contacts may not be optimal for some applications, or for some users in their systems. Some of these disadvantages could be overcome by use of multiple configurations of substrates with each specifically adapted to a specific pinout configuration. However, packaging a specific type of semiconductor die in multiple packages of different sizes and/or pinout configurations can increase overhead for both manufacturing and inventory management.